Strong evidence supports the concept that in different cells of early cleavage stages of a variety of embryos, there exists a divergence in genetic activity due to unequal distribution of cytoplasmic regulatory factors, initially localized in eggs during oogenesis. Numerous examples demonstrate the importance of the resultant nucleo-cytoplasmic interaction in early embryogenesis for regional tissue differentiation during later development. My primary objectives are: 1) to understand the biochemical basis underlying mechanisms of macromolecular and particulate localizations in eggs, and 2) to develop a molecular assay to identify localized cytoplasmic regulatory molecules that elicit the appearance of specific gene products in certain regions of the embryo. The specific aims of this proposal are: a) biochemically purify and characterize a mucopolysaccharide (MPS) which is localized in Fucus, and to determine the intracellular site(s) of synthesis, storage and transport by means of specific fluorescent-labeled lectins; b) determine by fluorescent microscopy and autoradiographic techniques, if the enzymatic sulfation of the MPS (which occurs just before its localization) is required for its transport, possibly via an endogenous electrical field; c) develop a coupled transcription-translation system in vitro using isolated nuclei; d) test the effect of cytoplasmic fractions from different locations within the embryo on nuclear expression in the vitro system. BIBLIOGRAPHIC REFERENCE: Brawley, S.H., R.S. Quatrano and R. Wetherbee. 1977 in press. Fine structure of Fucus embryos. III. Cytokinesis the multicellular embryo. J. Cell Science. Hogsett, W. and R.S. Quatrano. 1977 in press. Sulfation of fucoidan in Fucus embryos. III. Required for localization in the rhizoid wall. J. Cell Biol.